demo gallery

app/build.gradle

@@ -19,10 +19,12 @@ android {
 }
 
 dependencies {
-    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation fileTree(include: ['*.jar'], dir: 'libs')
     implementation 'com.android.support:appcompat-v7:26.1.0'
     implementation 'com.android.support.constraint:constraint-layout:1.1.2'
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'com.android.support.test:runner:1.0.2'
     androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
+    implementation 'com.android.support:design:26.1.0'
+    implementation 'com.squareup.picasso:picasso:2.3.2'
 }

app/src/main/AndroidManifest.xml

@@ -2,6 +2,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.example.nvmanh.demogallery">
 
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
+
     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"

app/src/main/java/com/example/nvmanh/demogallery/MainActivity.java

@@ -1,13 +1,93 @@
 package com.example.nvmanh.demogallery;
 
+import android.Manifest;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.net.Uri;
+import android.os.Build;
+import android.os.Environment;
+import android.support.annotation.NonNull;
+import android.support.design.widget.FloatingActionButton;
+import android.support.v4.content.ContextCompat;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
+import android.support.v7.widget.GridLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.util.Log;
+import android.view.View;
+import android.widget.ImageView;
+import android.widget.Toast;
+
+import java.io.File;
+import java.io.FileFilter;
+import java.util.ArrayList;
+import java.util.List;
 
 public class MainActivity extends AppCompatActivity {
 
+    private static final int REQUEST_PERMISSION = 1;
+    private static final String PATH = Environment.getExternalStorageDirectory().getPath().toString();
+    private static final String PATH_IMAGE = PATH + "/DCIM/Camera";
+    private static final String PNG = ".png";
+    private static final String JPG = ".jpg";
+    private static final String JPEG = ".jpeg";
+    private static final int LENGTH_CUT = 32;
+    private RecyclerView mRecyclerGallery;
+    private List<Picture> mPictures;
+    private RecyclerAdapterImage mAdapterImage;
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
+        initView();
+        mPictures = new ArrayList<>();
+        mRecyclerGallery.setLayoutManager(new GridLayoutManager(this, 2));
+        mAdapterImage = new RecyclerAdapterImage(this, mPictures);
+        mRecyclerGallery.setAdapter(mAdapterImage);
+        checkPermission();
+    }
+
+    private void initView() {
+        mRecyclerGallery = findViewById(R.id.recycler_gallery);
+    }
+
+    private void checkPermission(){
+        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)
+                    != PackageManager.PERMISSION_GRANTED) {
+                requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, REQUEST_PERMISSION);
+            }
+        } else {
+            getImageFromGallery();
+        }
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
+        if(requestCode == REQUEST_PERMISSION && grantResults[0] == PackageManager.PERMISSION_GRANTED){
+            getImageFromGallery();
+        } else {
+            finish();
+            super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+        }
+    }
+
+    private void getImageFromGallery(){
+        File file = new File(PATH_IMAGE);
+        File[] images = file.listFiles(new FileFilter() {
+            @Override
+            public boolean accept(File file) {
+                return file.getAbsolutePath().endsWith(PNG)
+                        || file.getAbsolutePath().endsWith(JPG)
+                        || file.getAbsolutePath().endsWith(JPEG);
+            }
+        });
+
+        for(File f : images){
+            Picture p = new Picture(f.getAbsolutePath().substring(LENGTH_CUT), f.getAbsolutePath());
+            mPictures.add(p);
+            mAdapterImage.notifyDataSetChanged();
+        }
     }
 }

app/src/main/java/com/example/nvmanh/demogallery/Picture.java

@@ -0,0 +1,27 @@
+package com.example.nvmanh.demogallery;
+
+public class Picture {
+    private String name;
+    private String pathImage;
+
+    public Picture(String name, String pathImage) {
+        this.name = name;
+        this.pathImage = pathImage;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getPathImage() {
+        return pathImage;
+    }
+
+    public void setPathImage(String pathImage) {
+        this.pathImage = pathImage;
+    }
+}

app/src/main/java/com/example/nvmanh/demogallery/RecyclerAdapterImage.java

@@ -0,0 +1,57 @@
+package com.example.nvmanh.demogallery;
+
+import android.content.Context;
+import android.support.v7.widget.RecyclerView;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import com.squareup.picasso.Picasso;
+
+import java.io.File;
+import java.util.List;
+
+public class RecyclerAdapterImage extends RecyclerView.Adapter<RecyclerAdapterImage.ViewHolder> {
+
+    private List<Picture> mPictures;
+    private Context mContext;
+
+    public RecyclerAdapterImage(Context mContext, List<Picture> mPictures) {
+        this.mContext = mContext;
+        this.mPictures = mPictures;
+    }
+
+    @Override
+    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
+        LayoutInflater inflater =
+                (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
+        View view = inflater.inflate(R.layout.item_image_recycler, parent, false);
+
+        return new ViewHolder(view);
+    }
+
+    @Override
+    public void onBindViewHolder(ViewHolder holder, int position) {
+        Picture p = mPictures.get(position);
+        holder.text.setText(p.getName());
+        Picasso.with(mContext).load(new File(p.getPathImage()))
+                .into(holder.image);
+    }
+
+    @Override
+    public int getItemCount() {
+        return mPictures.size();
+    }
+
+    public class ViewHolder extends RecyclerView.ViewHolder {
+        ImageView image;
+        TextView text;
+        public ViewHolder(View itemView) {
+            super(itemView);
+            image = itemView.findViewById(R.id.image_demo);
+            text = itemView.findViewById(R.id.text_name);
+        }
+    }
+}

app/src/main/res/drawable/ic_add_circle_black_24dp.xml

@@ -0,0 +1,5 @@
+<vector android:height="24dp" android:tint="#1CA5FF"
+    android:viewportHeight="24.0" android:viewportWidth="24.0"
+    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#FF000000" android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zM17,13h-4v4h-2v-4L7,13v-2h4L11,7h2v4h4v2z"/>
+</vector>

app/src/main/res/layout/activity_main.xml

@@ -1,18 +1,21 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<android.support.constraint.ConstraintLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:background="@color/color_black"
     tools:context=".MainActivity">
 
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Hello World!"
+    <android.support.v7.widget.RecyclerView
+        android:id="@+id/recycler_gallery"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        app:layout_constraintTop_toTopOf="parent"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintLeft_toLeftOf="parent"
         app:layout_constraintRight_toRightOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        />
 
-</android.support.constraint.ConstraintLayout>
+</android.support.constraint.ConstraintLayout>

app/src/main/res/layout/item_image_recycler.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="@dimen/dp_200"
+    android:layout_margin="@dimen/dp_2"
+    >
+
+    <ImageView
+        android:id="@+id/image_demo"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:scaleType="centerCrop"
+        />
+
+    <TextView
+        android:id="@+id/text_name"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:textSize="@dimen/sp_15"
+        android:textColor="@color/color_white"
+        android:layout_margin="@dimen/dp_2"
+        android:maxLines="1"
+        android:ellipsize="end"
+        android:layout_gravity="bottom|center"
+        />
+
+</FrameLayout>

app/src/main/res/values/colors.xml

@@ -3,4 +3,6 @@
     <color name="colorPrimary">#3F51B5</color>
     <color name="colorPrimaryDark">#303F9F</color>
     <color name="colorAccent">#FF4081</color>
+    <color name="color_white">#ffffff</color>
+    <color name="color_black">#000</color>
 </resources>

app/src/main/res/values/dimens.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <dimen name="dp_2">2dp</dimen>
+    <dimen name="dp_200">200dp</dimen>
+    <dimen name="sp_15">15sp</dimen>
+</resources>